Printing ink



, Patentedoct. 23, 1923.

UNITED STATES PATENT orrlcs.

WILLIAM J. MOELROY, OF NEW YORK, AND JOHN CLARKE, OF MANHASSE'I, NEW YORK, ASSIGNORS, BY MESNE ASSIGNMENTS, TO ALCHEMIC GOLD COMPANY, INC., OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

Y PRINTING INK.

No Drawing.

To all whom it may concern:

Be it known that we WILLIAM J. MoEL- ROY, a citizen of the Ilnited States, and a resident of the boron h of Manhattan, city, county, and State of ew York, and JOHN CLARKE, a citizen of the United States, and a resident of the village of Manhasset, town of North Hempstead, county of Nassau, and State of New York, have invented a new and useful Improvement in Printing Inks, of which the following is a description, as well as of the manner and process of making, constructing, compounding, and using the same, in such full, clear, concise, and exact terms as to enable any person skilled in the art or science to which it appertains, or with which it is most nearly connected, to make, construct, compound, and use the same.

Our invention relates to printing inks having a pigment ingredient liable to be discolored by the action of acid thereupon.

The general objects of our invention are to produce a printing ink free from acid or acidic constituents, and particularly to produce a non-corroding ink with metallic pigments and having the body and cOnsiSt' ency of the printing inks known as news-ink or book-ink; further objects are to provide a pigment vehicle of low volatility and high viscosity which will dry immediately upon being impressed by a heated impression member on the medium to be printed and will afford a protective coating to the pigment particles and will adhere permanently to printing ink Application filed March 2, 1923. Serial No. 622,436.

(3)It must be of such a character-that the action of the rolls will suflice to keep the components intimately mixed in the original proportions, i. e., the rolls must not squeeze the vehicle out of the pigment.

(4) It must not, when brought in contact by means, of the feed-rolls with the heated die, cake or dry on the latter or fill up the agreeable, or injurious.

(7) It must not, when compounded, de-

velop any greenish coloration in the vehicle.

(8) It must not, when compounded, develop any alteration in the color and lustre of the original pigment.

(9) It must not, when compounded, develop any alteration of body sufiicient to injuriously affect its working properties.

(10) It must unite intimately with the material impressed and form, when dried, a protective coating to the metallic particles of the pigment and bind themtogether in a film coating which is semi-elastic, vitreous, transparent, brilliant, and of high refractive index.

With the foregoing objects in view and with others as subsequently developed and pointed out herein, our invention consists in combining an insoluble neutral pigment such as the metallic pigments, and for example bronze powder, with a soluble neutral binder adapted when dissolved in a neutral solvent to form with the pigment a printing ink of the viscosity of book-ink, such a binder being afiorded by the synthetic gums known as the cumarone and indene resins, and for example by the cumarone gum known in the trade as Cumar; and such a solvent being afforded by the high-boiling, heavy-bodied solvents, exampled by terpineol, which has a refractive index of 1. 17 80 at 36 Fahrenheit and a density of .940.

The use of waxes or similar materials as binders, inwhole or in part, in the case of bronze inks meets the obstacle that because oflow'cohesiveness of the wax, the impression is not proof against rubbing, and because of lowrefractive index of wax, the impression is dull, and because of its lack of clarity the metallic particles are masked. With vehicles obtained from solutions of the neutralized gums as commercially obtainable, known as ester gum, some slight discoloration of the metallic powders is discernible upon long standing, and this is an objection where such shades are desired, for example, with bronze or gold or silver inks, that the greenish hue is a blemish. With other desired colors,

where greenish coloration is not objectionable and may be desirable, a vehicle comprising an ester gum is satisfactory. Where neutralization of the resin by esterification or otherwise is attained, the resin or rosin ester is the equivalent of the synthetic ums for all ink purposes. Thus, the neutra resin ester obtainable from the triglyceride of rosin is adapted for use in making a dark shade of gold ink and is preferable to Cumar because of its higher refractive index.

It will be obvious that the neutral vehicle obtainable from the neutral solvent and neutral binder may be used as a neutral base for variously pigmented printing inks adapted for color work on a heated press,

thus afiording immediate drying of the impressions which now, when cold-printed, must be carefully stacked and dried until handleable.

While neutralized. gums are preferable to a synthetic gum such as exampled, because the refractive index of the former is higher and therefore the particles of metal encysted in the binder appear more lustrous and brilliant, such preference is limited to the darker shades of gold inks because the neutralized gums are darker than desirable for I light shades of gold inks.

Resin solvents having a boiling point substantially below 200 C. cannot be used with a die heated to the temperature requisite to impart to the metallic pigments the desir d lustrous appearance of burnished me al when stamped. or embossed. Acidic solvents discolor metallic pigments. The ideal solvent should be clear, colorless, stable, highly viscous, a vigorous solvent for gums,

' absolutely neutral and of high boiling point,

and should combine with the gum to afford a vehicle having the characteristics first specified. Terpineol fulfils these requirements. Its body, chemical stability, rate of I Gold Lining.

volatilization, low cost, and the fact that it is obtainable in desired quantities commercially, render terpineol, at present, the preferred terpenylic solvent, but we do not in ten-d by our indication of such preference to limit our claims hereinafter made thereto, since certain other solvents have been used with excellent results and possess characteristics adapting them for use with certain classes of work. For example, where it is practicable to heat the impression head to a proportionally high temperature, as compared with the boiling point of tel-pineol, diethyl phthalate is an equivalent in all respects. characteristics essential to a proper vehicle for such inks, namely, a high boiling point, but not exceeding 300 (1., proper color, a high solvent action upon the binders named, both natural and artificial, and the requisite neutrality, but lacks the desired degree of viscosity. Cyclohexanol, an alcohol ob- 'tained by the hydrogenation of phenol, and certain hydronaphthalenes, namely, tetralin (essence) and decalin are also believed to possess the desired attributes so far as known to applicants, ,but are not obtainable at present in commercial quantities.

As an example of the preferred proportions of the preferred ingredients named:

Take by weight about 84 per cent of ter thereto about 66 per cent of bronze powder,

both by weight, and agitate this mixture by stirring until homogeneous. The desired consistency of book-ink will be obtained by observation of the precise amounts of metallic pigment necessary to give the desired consistency.

As the metallic pigmentfor gold inks above intended, we prefer a mixture of bronze powders made from the grades known ,commercially as Hemmerdingers Special No. 1 and Hemmerdin'gers Pale With 80 per cent of the former, equal in fineness to the Dupont bronze powders designated No. 3 S, is

mixed 20 per cent of the latter, which is a very finely ground bronze powder of the species known generally in the trade as lin ing, and equal in fineness'to the Dupont bronze powders designated as .No. 1 S.

The proportions above exampled maybe varied somewhat without appreciable variation of the product.

In selecting metallic pigments for gold inks, silver inks and the like, where pure colors are desired, it is important to note that certain bronze powders have-soluble dyes incorporated therein. If the vehicle is a solvent for such dyes, decoloration may result from their solution and decomposition. Wetherefore find it preferable to use metallic pigments free from dye-stufi's unless insoluble in the binder-solvent, since otherwise correction must be made by the addition of an inert masking dye or pigment.-

-By virtue of the com aratively high viscosity of the pigment ve icle afforded by the synthetic resins when dissolved in the heavybodied solvents therefor herein named, the

, ink obtained is especially valuable in that tendency of the powdered metallic pigments to settle is retarded.

Having thus described the preferred embodiment of our invention and the best method now known to us of producing and usefully applying same, we claim:

1. A neutral vehicle for pigments for printing ink composed'of a neutral binder and a neutral solvent for such binder.

2. A printing ink containing a metallic pigment and a neutral vehicle therefor.

3. A non-corroding printing ink containing a metallic pigment.

4. A printing ink composed of a neutral binder, a neutral solvent, and a neutral pigment.

5. A printing ink composed of-a neutral binder, a neutral solvent, and a metallicpigment.

6.. A printing ink composed of a neutral binder, terpineol, and a metallic pigment.

7. A neutral printing ink containing a metallic pigment and a vehicle therefor of high Viscosity and low volatility,

8. A neutral printing ink containing a pigment vehicle of high refractive index.

9. A neutral vehicle for metallic pigments for printing inks, such vehicle having a refractive index of approximately 1.5 at 36 F.

. WILLIAM J MGELROY.

JOHN CLARKE. 

